This is an archive of CompuServe forum messages from 1985 to 1995, as saved in transcripts by John Foust.
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#Continents in Collision
Message #176281
For all who have been lurking on the recent threads about continental drift and plate tectonics, and would like to know more about the subject, I'd like to recommend a book I found at Half Price Books yesterday, called CONTINENTS IN COLLISION. It's one of Time-Life Books' series about Planet…
Doug, >> >> Has there been any drilling and cores taken in the Hawaiian Islands? >> Probably, but I do not know of them. Wake me up when Mauna Loa spits out a piece of continental crust… I gather volcanic eruptions are liable to bring up occasional stray chunks of…
Don, >> My problem is with the Applachians as a product of the Alleghenian orogeny. It's clear that the mountains are post Pennsylvanian and pre-Cretaceous.
Don, >> On both sides we have these tidy folded mountains that are purported to have eroded only a little — only a few thousand feet of sediment missing — in 300,000,000 years. I don't have any problem with localized uplifts, but I have a lot of trouble with the…
Don, >> All of what you said seems reasonable to me except the erosion of the Applachians. The modern Applachian chain is very clearly a folded structure.
Doug, Mr. Dalziel may well have the right of it. I don't know. I only know that my text describes exotic terranes that don't clearly match either Laurentia or Baltica as being involved in the Taconic orogeny. >> In the next late-Devonian map they are more firmly connected and the…
Kamron, Sorry, I don't know. The references I have don't say anything about that, or if they do, I haven't found it yet. Jon W.
Kamron, >> Are there also granitic intrusions in the midst of the thrust faulting?
Kamron, >> If the east and west sides of the App. Mts. were different sections of crust it would go 15 miles deep or more..I would expect to see remnants of the crack…and how did they get welded together so well?
Doug, Disclaimer: I'm referring mainly to a basic geology/paleontology text dated 1989, so new info like your SA article may have changed some of this. But here's what this ref. says about the Appalachians: 1) In the Ordovician Period, Laurentia and Baltica were moving together, with a subduction zone in…
Doug, Offered FWIW: >> Indeed, I have heard that the Himalayas have been measured as still rising, though I cannot recall where.
Kamron, >> I have done clay modeling on a globe and the continents fit almost perfectly together in their current shape. The edge of the continents are virtually a vertical break and they fit together now. This cannot be just a coincidence. It appears that the margins have not changed…
Daniel, >> Where does this claim of fractional-distillation in magmas come from?
Kamron, >> Why would the transform faults still all line up across the Mid OCean Ridge after millions of years of moving in all directions why are they mostly lined up still?
Doug, Thanks for the reply. That's about what I figured, but I wanted to hear it from somebody who knew the subject better than I do. >> D2O and H2O differ in weight by a "hefty" ratio of about 20/18, where K40 and K39 would be a quarter as distinguishable…
#Isotopes in minerals
Message #170512
I have a question concerning the formation of mineral crystals during the process of igneous rock formation. I've seen people claim (or appear to claim) that "fractional distillation" can alter isotopic ratios so that minerals that solidify at different temperatures, or over different time spans, have different isotope ratios, thus…
Kamron, Hmm. "Soil and sand flows" sounds a lot like somebody's attempt to explain turbidity currents, which are basically the underwater equivalent of avalanches (on a steep slope) or slumps and mudflows (on a shallow slope). Once they get rolling they can build up a LOT of momentum, and can…
Kamron, How deep are the features you're talking about? Five meters? Ten? Twenty? Fifty? By some esitmates, worldwide ocean level may have been as much as a hundred meters lower than it is now during the Pleistocene ice ages. Are any of these features believed to be the result of…
Gary, >> So, if we believe that these reversal happen quickly, i.e., you wake up the next day and your compass needle points south instead of north, this would confuse the whole concept of App. polar wandering.
Gary, Let me see if I can help any re: polar wandering. You've got two separate and (probably) unrelated phenomena here. One is _polar wandering_, wherein the Earth's magnetic north pole moves in relation to 'true' geographic north, ie, the northern end of Earth's axis of rotation. We can detect…
Greg, >> But that is why I thought it didn't make sense. My understanding of GPS is that you fix your points from a series of measurements taken from sattelites. Thus, if point A and B somewhere on the earth, the distance between A and B are not relevant to…
Daniel, That figure came straight from the article I have. Don't blame me, blame the fool reporter. Jon W.
Greg, I _think_ (but am not at all sure) that they mean if you start at point A and head for point B 96km away, and navigate only by a GPS system, you will wind up at point B with a maximum error of 1mm plus or minus. Jon W.
Kamron, I don't _know_ that it's been done. I said I _think_ it has. I do know that I've seen estimated figures for plate motion stated in millimeters or centimeters per century. However, those could have come as easily from measuring seafloor spreading or motion relative to hot spots. So…
Kamron, >> Oh I think its marvelous we can locate to 50 meters. GPS is not going to be accurate enough to prove the motion of plates over a 20 year period, period.
Don, >> The problem is going to be separating rising due to "hot spot" thermal pluming from glacial rebound, that's known from Holocene marine fossils in the Champlain Valley to be 150 meters or more and is probably still happening.
Mike, >> Hey, here's a thought — where does Carbon-14 dating fit into all this? Anyone done anything with that? is that how they tell what geologic time period oil is from?
Al, According to the article, the GPS technology being used will yield an accuracy of 1 millimeter in 60 miles. Jon W.
#Adirondacks Hot Spot
Message #166355
The following info comes from an AP article dated yesterday: A team of geologists and graduate students are conducting a study in the Adirondack Mountains in upstate New York which they hope will show the existence of a 'hot spot' in the Earth's mantle deep below the area. Mantle hot…
Kamron, >> How is it all so …..? fresh? Open up a supply to the air and its tar in a few hundred years. This almost proves it only cooked for a few days or weeks.
Kamron, You want it, you got it. The book is: EARTH SCIENCE, 5th Edition Edward J. Tarbuck & Frederick K. Lutgens Merrill Publishing: 1988 The photo I was referring to is on p.80. Jon W.
Martin, Nope, no dinos from La Brea. The tarpits produce only Recent and Pleistocene fossils. Jon W.
Kamron, >> The meanders occur in valleys that have been infilled with sediments and sands.I don't remember seeing any rivers creating a meandering pattern in deep rock canyons.
Kamron, >> The water seeks a short cut and once the river had cut lower on one side of the tower it would never find it easier to return again over the high side let alone do this over and over back and forth creating the massive tower.
Glenn, None of my references here at home have much on the tar pits, but if I were you I'd go to the nearest good library and look for books about the Cenozoic Era and its lifeforms. Any book about recent mammals is likely to mention the tar pits, because…
Sherry, The US Geological Survey might have what you want. They should have an office in the nearest major city. Jon W.
Leland, Earthquakes can happen anywhere you have active faults in the bedrock. They aren't limited to plate margins and volcanic regions. No one is quite certain of the origin of intra-plate faults like the New Madrid Fault. One school of thought holds that the New Madrid fault complex is a…
Spencer, >> One wonders if that footprint of Heracles (or Hercules, if you prefer the Roman form of the name) was actually an exposed dinosaur footprint? Something to speculate on, mayhap.
#16075-
Uniformitarianism-valid?
Message #16101
Jon, Sorry, what I posted was all I know on that particular subject. >> There is a difference between the limited variation found in the genetic pool of any given species and the kind of changes envisioned by the theory of evolution. Creationists have no argument with the kind of…
Leland, >> Is my supposition right that rocky foundations result in less quake damage than houses build on loose soil?
Francois, You might also want to post this in the Dinosaur forum (GO DINO). There are a number of amateur and pro paleontologists who hang out over there. Jon W.
Morgaan, >> That's one of my latest current hairbrain theories about why it's so bad in Kobe. The waveforms ran across the seafloor from Awiji Island into the soft sand and landfill of Kobe. Maybe what happened when the waves hit the mountains is that some of the energy was…
New dino/continent drift
Message #163712
Today (1/19), Argentine paleontologists reported the discovery of a new type of dinosaur that supports the theory of continental drift, in that it supports the idea that South America and Africa were once joined as a single landmass. A local resident discovered the fossil at La Picassa, which is in…
Greg, >> I think you are right. Floods are very common, it is not surprising that they occur in many myths. Also, since 10,000 years age, many many (the majority?) of people have moved (as cultural lineages, if you will) from one place to another. So a flood myth found…
Kamron, >> The point here is that the Rise begins with a very fractured and craggy beginning and as we move away from the rise the floor gets smoother in comparison to the rise.
Doug, >> >> 1. The ocean floors aside from the rises, seamounts, and continents are relatively smooth and show none of the bulging , cracking, waving, splitting, piling up, ect that would be evident if all the motions in the plates were taking place.
Gary, >> I can't understand why you refute the above, but hold onto the "other" Ness-type animals belief when there is also no conclusive proof of their existence? Maybe I misunderstood you in regards to these animals.
Kamron, >> The earth definitely shows different ocean levels or total amount of water. My glib explanation at this point is that the earth received water from other sources. The rings of some of the planets I believe also arrived from other sources. It is obvious that Mars lost some…
Gary, >> It goes back to the age old question of "What is the meaning of life?" Well, I read a good response to this from an atheist, "There is no meaning to life, per se; however, it is up to us to pump meaning into life on a daily…
PS: Sorry for the vehemence; it's not directed at you. It's just that my blood starts boiling every time I think about this for too long. It frustrates me no end that so much potential talent is wasted because teachers don't know how to teach science properly. Jon W.
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